Low power rf control system

ABSTRACT

A low power rf control system includes a controller that operates at a low clock speed when an associated rf receiver is deenergized and a high clock speed when the controller energizes the receiver. The receiver can be on for a short period, off for a short period if no preamble pulses from a remote control device are received, on for a short period, and then off for a longer period until the next cycle. The receiver remains on to process a command signal when a preamble signal is detected. A DC-DC down converter can be used as a power supply for the receiver, and a SAW resonant circuit can be used as an IF oscillator for the receiver. An LC filter can be associated with the receiver for filtering the IF signal.

I. FIELD OF THE INVENTION

The present invention relates generally to radio-frequency (rf) controlsystems for controlling such things as window coverings, awnings,security screens, projection screens, lighting systems and controls,battery operated radios, televisions, and stereos, and the like.

II. BACKGROUND

Window coverings that can be opened and closed are used in a vast numberof business buildings and dwellings. Examples of such coverings includehorizontal blinds, vertical blinds, pleated shades, roll-up shades, andcellular shades made by, e.g., Spring Industries®, Hunter-Douglas®,Levellor®, and Somfy®. It is to be understood that while the remotecontrol of window coverings is envisioned and used as one exemplaryapplication, the principles set forth herein may be applied to othersystems, including, without limitation, awnings, security screens,projection screens, lighting systems and controls, battery operatedradios, televisions, and stereos, and the like wherein conservation ofbattery power is desired.

Several effective systems for advantageously either lowering or raisinga window covering, or for moving the slats of a window covering betweenopen and closed positions, have been provided. Such systems aredisclosed in U.S. Pat. Nos. 6,189,592, 5,495,153, and 5,907,227,incorporated herein by reference. These systems include a motor drivengear box that is coupled to a tilt rod or roller tube of the windowcovering. When the motor is energized, the tilt rod (or roller tube)rotates clockwise or counterclockwise. These systems can be, e.g.,operated via a remote control unit. Typically, these remotely operatedsystems include an infrared (IR) transmitter in the remote control unitand an IR receiver in an actuator that is mechanically coupled to theblinds. In most cases, the receiver remains awake constantly or pulsesbetween on and off. Thus, when a signal is sent by the transmitter, thereceiver can receive it, but in the case of pulsed receivers, only whenthe receiver is in the “on” state. The receiver can require a relativelyhigh amount of current in order to properly operate. As a result, if thereceiver is powered by a direct current power source such as a batteryit can quickly drain the battery. On the other hand, continuouslypulsing the receiver between power on and power off can help increasebattery life, but the battery still can relatively quickly lose power,since the duty cycle between “off” and “on” must be relatively short, toavoid missing a user signal. Even then, unacceptable delay can existfrom when a user toggles a control button on the remote and the windowcovering starts to move.

Accordingly, the present invention recognizes a need for a controlsystem for a motorized window covering that further conserves power, andthat has a short response time.

SUMMARY OF THE INVENTION

A radio-frequency (rf) control system for a component such as but notlimited to window coverings, awnings, skylight covers, and screens,includes a remote control device that is manipulable by a user totransmit a wireless rf signal. An rf receiver is associated with thecomponent and is configured for processing the rf signal. Also, acontroller is associated with the component for controlling thereceiver. The controller saves power by only periodically energizing thereceiver. In one embodiment, the remote transmits a series of preamblepulses prior to transmitting a command signal. In this embodiment, thecontroller causes the receiver to be energized for a first energizedperiod, then to deenergize for a short period if no preamble signal isdetected, then to energize for a second energized period, and then todeenergize, if no preamble signal is detected, for long period longerthan the short period, prior to once again reenergizing the receiver.

Or, assuming that the preamble pulses repeat, e.g., every fivemilliseconds, a first receiver energization might be needed to samplewhether a preamble is detected. Recognizing that a failure to detect thepreamble could mean that no preamble has been transmitted by the remotebut could also mean that the receiver was energized during an off periodof an existing preamble, the receiver can be energized a second timeafter a rest period the length of which ensures detection in at leastone of the time periods of a preamble pulse if a preamble has beengenerated.

In another embodiment, the remote transmits a single long preamble pulse(of, e.g., sixty milliseconds) prior to the command signal, and thecontroller energizes the receiver temporarily sometime within the periodof the preamble pulse. In any case, once a preamble is sensed, thereceiver remains energized to detect the ensuing command signal.

In a preferred embodiment, the preamble signal includes plural pulses,with each pulse having a duty cycle in excess of fifty percent (50%).The preamble includes at least six pulses and more preferably twelvepulses.

As set forth further below, in some embodiments the controller operatesat a low clock frequency during at least most of the long period and ata high clock frequency at least when the receiver is energized. Thecontroller may operate at an intermediate frequency between the low andhigh frequencies just prior to energizing the receiver after the longperiod, if advantageous to the controller.

If desired, at least one bypass capacitor can be electrically connectedto the receiver and to ground. As recognized herein, the time to chargea receiver's bypass capacitors varies with capacitance, with largercapacitors yielding better receiver performance once charged butrequiring more time to charge and, hence, more delay in rendering thereceiver operational. Accordingly, in a preferred embodiment the bypasscapacitor can have a capacitance of below five hundred picoFarads (500pF). Plural bypass capacitors may be provided with at least one having acapacitance not substantially more than one hundred picoFarads (100 pF).We have found that these small capacitances permit faster receiverresponse time without unduly reducing receiver performance.

Further, some embodiments may use a surface acoustic wave (SAW)resonator circuit to establish an intermediate frequency (IF) oscillatorfor the receiver. An LC filter can be associated with the receiver forfiltering an IF signal, when a SAW resonator is used. Also, thecomponent can be powered by at least one battery, and the system caninclude a DC-DC down converter electrically interposed between thebattery and receiver to provide a voltage to the receiver with asignificant reduction in battery drain at minimal power loss.

In another aspect, a radio-frequency (rf) control system for a componentincludes a remote control device manipulable by a user to transmit awireless rf signal, and an rf receiver associated with the component andconfigured for processing the rf signal. A controller controls thereceiver. The controller operates at a low clock frequency during atleast most of a receiver sleep period and at a high clock frequency atleast when the receiver is energized.

In still another aspect, a radio-frequency (rf) control system for acomponent includes a remote control device manipulable by a user totransmit a wireless rf signal, and an rf receiver associated with thecomponent and configured for processing the rf signal. A controllercontrols the receiver. At least one bypass capacitor is electricallyconnected to the receiver and to ground. The bypass capacitor has acapacitance of below five hundred picoFarads (500 pF).

In yet another aspect, a radio-frequency (rf) control system for acomponent includes a remote control device manipulable by a user totransmit a wireless rf signal, and an rf receiver associated with thecomponent and configured for processing the rf signal. A controllercontrols the receiver. A surface acoustic wave (SAW) resonator circuitestablishes an intermediate frequency (IF) oscillator for the receiver.As recognized herein, such a filter advantageously starts up faster thana conventional phase-locked loop oscillator.

In another aspect, a radio-frequency (rf) control system for a componentincludes a remote control device manipulable by a user to transmit awireless rf signal, and an rf receiver associated with the component andconfigured for processing the rf signal. A controller controls thereceiver. The present invention recognizes that the system battery mightprovide a higher voltage than is needed for the receiver. Accordingly, aDC-DC down converter can be electrically interposed between the batteryand receiver to provide a voltage to the receiver.

In another aspect, a radio-frequency (rf) control system for a componentincludes a remote control device manipulable by a user to transmit awireless rf signal, and an rf receiver associated with the component andconfigured for processing the rf signal. A controller controls thereceiver. The controller adaptively adjusts a noise threshold abovewhich a carrier must be detected to indicate the presence of a controlsignal. The present invention understands that this feature reduces theamount of time that the receiver undesirably is energized in response tonoise rather than desired signals from the transmitter.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a window covering actuator, shown in oneintended environment, with portions of the head rail cut away;

FIG. 2 is a block diagram showing the receiver and controller of thepresent invention;

FIG. 3 is a schematic diagram of the signals from the remote controlunit in a first paradigm;

FIG. 4 is a schematic diagram of the signals from the remote controlunit in additional paradigms;

FIG. 5 is a circuit diagram of the preferred DC-DC converter; and

FIG. 6 is a flow chart of the present logic.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, for illustration purposes a motorizedwindow covering is shown, generally designated 10, that includes anactuator such as a rotatable rod 12 of a window covering 14, such as butnot limited to a shade assembly having raisable (by rolling up) andlowerable (by rolling down, or unrolling) shade 16. As shown, the tiltrod 12 is rotatably mounted by means of a block 18 in a head rail 20 ofthe window covering 14. In some embodiments the tilt rod 12 is a tube.

While a roll-up shade is shown as but one non-limiting example of anapplication of the present low power rf control system, it is to beunderstood that the rf control system disclosed herein can be used in awide range of other applications to control devices sought to becontrolled. For example, the invention applies to raisable and lowerablepleated shades and cellular shades such as those commonly marketed underthe trade names “Silhouette”, “Shangri-La”, etc. as well as to projectorscreens, awnings, etc. that can be raised and lowered. Moreover, theinvention may also apply to tilt-only systems. Thus, for example, therod 12 may be a roll-up rod of a shade, awning, or projector screen orsecurity screen, or a tilt rod of a horizontal (or vertical) blind, orother like operator. It is thus to be further understood that theprinciples of the present invention apply to a wide range of windowcoverings and other objects including, but not limited to the following:vertical blinds, fold-up pleated shades, roll-up shades, cellularshades, skylight covers, etc. Powered versions of such shades aredisclosed in U.S. Pat. No. 6,433,498, incorporated herein by reference.Still further, the rf control system can be used to control lightingsystems and controls, as well as battery operated radios, televisions,and stereos, and the like.

In the non-limiting illustrative embodiment shown, the window covering14 is mounted on a window frame 22 to cover a window 24, and the rod 12is rotatable about its longitudinal axis. The rod 12 can engage auser-manipulable baton (not shown). When the rod 12 is rotated about itslongitudinal axis, the shade 16 raises or lowers between an openconfiguration and a closed configuration.

FIG. 1 shows that the actuator 10 can include a control signalgenerator, preferably a signal sensor 26, for receiving a user commandsignal. Preferably, the user command signal is generated by a hand-helduser command signal generator 28, which is a radio-frequency (RF)remote-control unit operating at, e.g., between one hundred MegaHertzand one thousand MegaHertz and perhaps between four hundred and fivehundred megaHertz (400 MHz-500 MHz), more preferably at 433 MHz, andmore preferably still at 433.42 MHz. The user command signals caninclude open, close, raise, lower, and so on. A manual operation switch29 can also be provided for locally operating the motor disclosed below.

An electronic circuit board 30 can be positioned in the head rail 20 andcan be fastened to the head rail 20, e.g., by screws (not shown) orother well-known method. The preferred electronic circuit board 30includes the below-described microprocessor or controller for processingthe control signals. Also, the circuit board 30 includes an rf receiveras set forth further below that is connected to controlled by themicroprocessor or controller.

FIG. 1 shows that a small, lightweight electric motor 32 is coupled to agear enclosure 34, preferably by bolting the motor 32 to the gearenclosure 34. The gear enclosure 34 is keyed to the rod 12, so that asthe gears in the gear enclosure 34 turn, the rod 12 rotates.

It is to be understood that the motor 32 is electrically connected tothe circuit board 30. To power the motor 32, one or more (four shown inFIG. 1) primary dc batteries 36, such as type AA alkaline batteries orLithium batteries, can be mounted in the head rail 20 and connected tothe circuit board 30. Preferably, the batteries 36 are the sole sourceof power for the motor, although the present invention can also beapplied to powered shades and other objects that are energized from thepublic ac power grid.

As more fully disclosed below, a user can manipulate the signalgenerator 28 to generate a signal that is sensed by the signal sensor 26and sent to signal processing circuitry in the circuit board 30. Inturn, the electrical path between the batteries 34 and the motor 32 isclosed to energize the motor 32 and move the window covering open orclosed in accordance with the signal generated by the signal generator28, under control of the processor on the electronic circuit board 30.

In the case of other systems, the processor on the circuit board 30might, for instance, energize a lighting system when an appropriatecommand signal is received, or raise or lower an awning or screen, oractivate or deactivate a battery-operated radio, TV, or stereo, inaccordance with present principles.

Now referring to FIG. 2, the receiver, controller, and supportingcircuitry on the circuit board 30 in the device being controlled can beseen. In overview, the present receiving system shown in FIGS. 2 and 3uses very low power, and thus significantly prolongs battery life. Asset forth further in detail below, in the exemplary non-limitingembodiment and owing to the inventive features herein, the receiver isvery sensitive and it turns ON, completely stabilizes, and startsreceiving signals in only seventy microseconds.

A rf receiver 40 is shown that is connected to an antenna 42 through apreamplifier 44 and a surface acoustic wave (SAW) filter 46 inaccordance with rf principles known in the art. The non-limitingexemplary rf receiver 40 is a Phillips superheterodyne SA636 receiverintegrated circuit. Accordingly, while details of its pins and pinconnections are shown in FIG. 2, only the salient modifications of thepresent invention will be discussed, it being understood that theprinciples set forth herein generally apply to other receivers as well.

As shown, the receiver 40 includes a local oscillator 48 fordownconverting the rf signal to IF. The Local oscillator 48 can be aconventional phase locked loop (PLL) synthesizer but in the preferredembodiment the Local oscillator 48 is established by a surface acousticwave (SAW) resonator circuit, which can start up much faster than a PLLsynthesizer and, as recognized by the present invention, consequentlysave energy by reducing start up time. The SAW resonator circuitpreferably can start up in ten to fifteen microseconds.

As also recognized herein, however, it might happen that an availableSAW resonator circuit does not provide sufficient frequency separationthat otherwise would be required to allow the use of off-the-shelf IFfilters. Accordingly, in the preferred embodiment an LC filter 50,preferably a discrete elliptic LC filter with low value couplingcapacitors C23, C25, is associated with the receiver 40 for filteringthe IF signal. The LC filter 50 includes first and second inductors L8,L9 (with exemplary non-limiting inductances, in Henries, indicated inFIG. 2) in series with the coupling capacitors C23, C25 and in parallelwith a circuit capacitor C38. A ground capacitor C24 can be located inseries between a tap between the inductors and ground as shown.

Furthermore, the preferred receiver 40 is associated with bypasscapacitors C15, C17, C18, C19, C22, C37, C20, and C21 that connect thereceiver 40 to ground as shown and that have inventively lowcapacitances, much lower than the conventional capacitance of one tenthof a microfarad for the particular exemplary rf receiver 40 designshown. More particularly, in the non-limiting embodiment shown thebypass capacitor C15 has a capacitance of two hundred twenty picoFarads(220 pF), and the remaining bypass capacitors have capacitances of onehundred picoFarads (100 pF). The present invention has discovered thatthese low capacitances allow for much faster start up time of thereceiver 40 without, as might otherwise be expected, unduly degradingreceiver sensitivity.

Additionally, the rf receiver 40 preferably is powered by three voltsdirect current (3 vdc) produced by a DC-DC down converter 52 that isinterposed between the batteries shown in FIG. 1 and the receiver 40.The details of the converter 52 are set forth more fully in reference toFIG. 5 below. Less desirably, a series regulator could be used as aDC-DC converter, or the receiver can be powered directly from a threevolt battery or so-called “coin cell”. The preferred converter set forthbelow is preferred because it converts battery voltage to three voltsusable by the receiver 40 with little power loss, further prolongingbattery life.

Thus far, the components discussed above are in the main related torapidly energizing the rf receiver 40 to reduce start up time of thereceiver and, hence, to conserve power. FIG. 2 also shows components,however, that function to process command signals received from theremote control device 28 in FIG. 1 when the receiver 40 is energized. Tounderstand how these components of FIG. 2 work, temporary reference ismade to FIG. 3.

To provide compatibility with a system which may provide a preamble ofsix or twelve preamble (pre-synchronization, non-data command) pulses of45% to 55% duty cycle at the rate of 200 pulses per second, a preferredembodiment might be implemented wherein the remote control devicetransmits twelve preamble pulses at a 55% duty cycle. Other pulses ratesand numbers of pulses may be used. The governing criteria can includethe acceptable time delay between operator command and system response,the amount of this delay period that can be allocated to the preamble,and the duty cycle that is permitted. For example, a single longpreamble pulse of, e.g., sixty milliseconds can be used, in which casethe receiver need be powered up to sample only once during the period,or sixty pulses at a rate of 1000 pulses per second and a duty cycle of55% can be used.

In the particular embodiment shown in FIG. 3, wherein twelve pulses at aduty cycle of 55% are used, the signal from the remote control device 28(FIG. 1) can include plural preamble pulses (labelled “pre sync” in FIG.3) followed by a single synchronization pulse (labelled “sync” in FIG.3) and a long encoded control signal, which can be a 56 bit Manchesterencoded signal. Six to twelve preamble pulses may be used in somenon-limiting embodiments. The preamble pulses have duty cycles in excessof fifty per cent, and preferably have duty cycles of around 55%. In oneembodiment, to achieve this each preamble pulse can be 2.75 ms in lengthwith 2.25 ms between pulses. The synchronization pulse can be 4.8 ms inlength and can be separated from the last preamble pulse by 640 μS.After the encoded control signal is sent, 62.5 ms can elapse to thestart of the next synchronization pulse.

Those skilled in the art will appreciate that the above-describedamplitude shift keying, or on-off keyed, modulation permits sampling thereceiver as rarely as possible for power conservation while ensuringthat at least part of the preamble is detected to indicate a controlsignal is about to be received.

As mentioned above, however, other preamble pulse generation anddetection paradigms can be used. If the remote can transmit, prior tothe command signal, a single long preamble pulse, for instance, ofaround sixty milliseconds, the controller can energize the receivertemporarily sometime within the period of the preamble pulse. In anycase, once a preamble is sensed, the receiver remains energized todetect the ensuing command signal.

Additional examples of preamble pulse generation and detection paradigmsare shown in FIG. 4, the various examples of which show a series ofpreamble pulses “P” having a period (labeled “single pre-sync pulseperiod” in example 1), e.g., of five milliseconds, for illustration. InExample 1, twelve presynchronization pulses “P” at a duty cycle of 55%are generated by the remote control device. Wake-up bars “B” representwhen the receiver is energized by the controller. As shown in Example 1,the wake-up events occur in groups of twos. In example 1, the wake-upbars “B” of a group are paired one-half of one pulse period apart. Thisensures that if the first wake-up event occurred when no pulse “P” wasbeing transmitted but a signal from the remote control devicenonetheless has been generated by a user, the second wake-up event willoccur during (and, hence, the receiver will detect) a subsequent pulse“P”, owing to the 55% pulse duty cycle. The next group of two wake-upevents B′ occurs before the end of the length of an entirepresynchronization cycle period as shown in FIG. 4.

Example 2 shows much the same paradigm except that the pulse “P” operateat only a 45% duty cycle. In this example, the receiver wake-up eventsoccur in groups of threes, with the wake-up events of a group spacedone-third of a pulse period apart from each other, to ensure detectionof a pulse “P” if the user has generated a command signal using theremote control device. The next group of two wake-up events B′ occursbefore the end of the length of an entire presynchronization cycleperiod as shown in FIG. 4.

Example 3 shows yet another paradigm wherein only a single longpresynchronization pulse “P” is generated by the remote control device,and two receiver wake-up events B, B′ are generated over a time spanthat is less than the pulse period. It may now be appreciated that inall three of the first three examples shown in FIG. 4, plural groups ofwake-up events occur within the total time span of thepresynchronization signal, also referred to herein as a “preamble”, withplural events of a single group occurring within a single pulse period.

Examples 4 and 5 in FIG. 4 show paradigms wherein plural wake-up eventsoccur within the total time span of the presynchronization signal butonly a single wake-up event occurs within any given pulse period. Inexample 4, twelve pulses “P” are generated by the remote control deviceat a duty cycle of 55%, with two receiver wake-up events B, B′ per cyclebeing temporally spaced from each other less than one-half of the totalpresynchronization signal period as shown. In contrast, in Example 5twelve pulses “P” are generated by the remote control device at a dutycycle of 45%, with three receiver wake-up events B, B′, B″ beingtemporally spaced from each other less than one-third of the totalpresynchronization signal period as shown.

Referring back to FIG. 2, a slow receiver signal strength indicatorfilter 54 and a fast receiver strength indicator filter 60 are connectedto the receiver 40 and to a controller 56, for processing as followsprior to analysis by the controller 56 discussed below in reference toFIG. 6. Both filters 54, 60 can be implemented by Salen key filters,with the slow filter 54 having a time constant of, e.g., two hundredmicroseconds (200 μs) and the fast filter 60 having a time constant of,e.g., ten microseconds (10 μs). The output of the fast filter 60 is usedby the microcontroller 56 to determine whether a carrier signal has beendetected. When a carrier signal is detected, the microcontroller 56 usesthe output of the slow filter 54 to detect the continued presence (ornot) of a signal to reduce the effect of noise. A comparator 58 that isconnected to the microcontroller 56 receives the output of the slowfilter 54 to provide a digital signal to the microcontroller 56. This isoften referred to as a “slicer”.

Turning to the controller 56, in a non-limiting embodiment thecontroller 56 may be implemented by an IC type 16LF819-I/SO made byMicrochip Technologies, it being understood that the present principlesapply to any controller (which may be variously referred to as a“microcontroller”, “processor”, “microprocessor”, or “central processingunit”) that functions as set forth herein. As shown, a power on resetcircuit 62 can be provided to reset the controller 56 when it isinitially powered on.

As intended herein, not only does the controller 56 process the signalfrom the receiver 40 to determine how to control, e.g., systems 64, 66(such as component motors, light switches, etc.) having respectiveinterfaces 68, 70, but it also turns the receiver 40 on and off inaccordance with disclosure below. To this end, a switch 72, which can beimplemented by a PNP transistor, is provided that is selectively closedby the controller 56 to connect the voltage from the converter 52(“+3.0V” in FIG. 2) to the receiver 40 (as indicated in FIG. 2 by the“3V RF” pin) when the logic below determines to turn on the receiver 40.Also, the controller 56 may be programmed to accept commands from aparticular remote control device. In this case, a program light emittingdiode (LED) 74 can be illuminated by the controller 56 when a usersimultaneously depresses a program pushbutton 76 with appropriatemanipulation of the remote control device 28 shown in FIG. 1, toindicate that the signal from the remote control device 28 is stored bythe controller 56 for future recognition.

The specific type of component control logic afforded by the controller56 varies from component to component, and is not central to the presentlow power rf control system. Details of one type of control logic thatthe controller 56 can implement in the context of roll-up shades are setforth in U.S. Pat. No. 6,060,852, incorporated herein by reference.Other types of control paradigms can be used to respond touser-generated command signals from the remote control device 28, e.g.,simple “open” and “close” commands for window coverings, “up” and “down”commands for screens, and “on” and “off” commands for lighting systems,radios, TVs, and other electronic or electric components. The controller56 decodes data in the control signal based on the timing of pulsestherein.

Before detailing how the controller 56 controls the receiver 40 toreduce power consumption, reference is made to the circuit diagram inFIG. 5 of a preferred non-limiting DC-DC converter 52, which, it will berecalled, operates to convert battery voltage to three volts for use bythe receiver 40, with minimal power loss. The specifications for thepreferred non-limiting converter 52 are:

a. Input Voltage: 5 V to 14 V b. Output Current: 0 mA to 15 mA c.Efficiency: 70% minimum at 50 uA out 80% minimum at 15 mA out

The present invention makes the following observations regarding theadvantages of using a DC-DC converter. It is desirable to operate smallshades for about four years using an “AA” battery, which provides anaverage current for the period of about seventy five microAmperes (75μA). Were a linear regulator instead of a DC-DC converter used to powerthe receiver, it would consume about fifty microAmps, and the shadecontroller another ten microAmps, leaving only fifteen microAmps todrive the shade. If the small shade is completely raised and loweredonce a week, the average current required is about seven microAmps, sothe battery will last four years if the shade is operated no more thantwice per week. Use of a DC-DC down converter, however, results inreducing receiver current requirements to less than twenty microAmps,enabling about three times as much operation over a four year period.For this reason, the DC-DC converter is preferred in the exemplarynon-limiting embodiment.

Referring to the schematic diagram of FIG. 5, the non-limiting exemplaryDC-DC converter 52 operates as follows. “IC6” on the left hand portionof the circuit is a micropower linear regulator that provides power thecircuit before the converter 52 begins to operate, via resistor R61 andpin 2 of the dual diode D4. Also, the regulator “IC6” provides areference voltage for pin 4 of the comparator IC7 via resistors R44 andR43. When the feedback from the +3.0V provided by resistors R46 and R45is lower than the reference voltage, the output of the comparator isdriven low, turning transistors Q10 and Q9 ON, raising the input toinductor L1 to the battery voltage. This causes current to start to flowthrough inductor L1, charging the output filter capacitors, C10 and C33.Capacitor C41 provides AC hysterisis to keep the output of comparatorIC7 low until the charge drains off of capacitor C41. After a timedetermined primarily by the time constant formed by capacitor C41 andresistors R46 and R45, pin 3 rises above pin 4 of comparator IC7,driving the output of comparator IC7 high, which turns OFF transistorsQ10 and Q9. This interrupts the flow of current though transistor Q9.However, inductor L1 opposes any abrupt change of current flowingthrough is, so the input of inductor L1 is lowered until it findsanother source of current. Just after, it passes ground potential, thetwo diodes in D6 turn ON to provide a source of current. The voltageacross the inductor, which was positive on the input, is now negative,about 3.3V, slowing and ultimately stopping the flow of current. Whenthis current stops, the input of inductor L1 rises, the diodes D6 turnOFF, and eventually the voltage across the inductor is zero. The chargethat flowed through inductor L1 is stored in capacitors C10 and C33.Because of the large capacitance of capacitor C10, the change in voltagein the output +3.0V is less that 3 mV, providing excellent regulation tothe pulse loads required by the receiver 40.

Because of the wide range of battery voltages used in the variouscontrolled devices, a second feedback path can be provided to supplementthe path through resistor R46. If inductor L1 were always connected tothe battery for a fixed period, regardless of battery voltage, then theamount of charge transferred from the battery to the output capacitorswould vary as the square of the voltage across inductor L1. If the timethat inductor L1 is connected to a low battery voltage is adequate toprovide the current to operate the receiver 40, at high batteryvoltages, inductor L1 would saturate, defeating the purpose of theconverter. Accordingly, the second feedback path is provided by resistorR47 and diode D5. This feedback is proportional to the battery voltage,but only during the time that transistor Q9 is conducting, so that thetime that transistor Q9 conducts with a high battery voltage is muchshortened compared to a low battery voltage. The purpose of the diode onpin 1 of D4 is to prevent the voltage on pin 3 of comparator IC7 fromrising excessively above the supply voltage, which if it were allowed todo might damage comparator IC7. Capacitor C40 provides a filter for thereference voltage to pin 4 of comparator IC7, keeping the voltage freeof noise. Capacitor C36 is an output capacitor required to stabilize thecomparator IC7.

Accordingly, in the preferred non-limiting embodiment shown, theconverter 52 operates efficiently over a wide range of loads because:

a. very small reference and feedback currents are used—280 nA.each.

b. a low current comparator is used, typically 600 nA

c. minimal switch drive current, 400 nA, on average is used

d. a low forward voltage in D6 is used

e. high product of inductor time constant times its saturation currentis used

It is also preferred to have a storage capacitor (C10) with lowequivalent series resistance (ESR) to minimize the ripple voltage on theoutput.

Now referring to FIG. 6, the details of the preferred logic used by thecontroller 56 to energize and deenergize the receiver 40 may be seen. Asintended by the present invention, when the user toggles a commandbutton on the remote control device 28 shown in FIG. 1, an rf commandsignal is generated that is preceded by a repeating preamble (indicatinga carrier) indicating that command data is to follow. The preferredpreamble includes plural pulses, each having a period of fivemilliseconds and a duty cycle in excess of fifty percent (50%), e.g.,each pulse can have a duty cycle of 55%. The preamble includes at leastsix pulses and more preferably includes twelve pulses. The preamble isperiodically transmitted in accordance with disclosure below.

With this in mind, the logic to control energizing the receiver 40begins at state 100 and proceeds to decision diamond 102, wherein it isdetermined whether it is time to wake up (energize) the receiver. If itis, the logic continues to block 104 to raise the clock frequency of thecontroller 56, which runs at 30 KHz while the receiver 40 is in the longsleep period, to an intermediate frequency, e.g., 125 KHz. The clockruns at this intermediate frequency for a predetermined start up time,e.g., two milliseconds, at which point the logic moves to block 106 toraise the clock frequency to 4 MHz. The receiver is then energized atblock 108 for a short wake-up time period, e.g., eighty microseconds,taking advantage of the components discussed in reference to FIG. 2 torapidly achieve operating effectiveness.

The reason for the above operation is that as recognized herein, thecontroller 56 must be completely ready to analyze the output of thereceiver 40 during the period when the receiver 40 is powered, whichrequires the controller to run at a 4 MHz clock frequency. However, whenrunning at this frequency, comparatively much power is consumed, so thatwhen the receiver is not energized the controller operates at only 30KHz, conserving power. But as further understood herein, the controller56 has a start up time of, e.g., two milliseconds when transitioningfrom 30 KHz to a higher frequency, but can almost instantaneously movefrom an intermediate frequency (e.g., of 125 KHz) to the high frequency(e.g., 4 MHz) required for processing signals from the receiver 40.Running at the high frequency during this start up time, as recognizedherein, consumes too much power. Accordingly, the controller 56 operatesat the intermediate frequency during the start up time to furtherconserve power, and then, once transitioning has been completed,operates at the requisite high frequency.

When the receiver 40 is energized at block 108, the logic moves todecision diamond 110 to determine whether a preamble has been detectedduring the wake-up time. If so, the receiver remains energized at block112, and the command signal from the remote control device 28 isprocessed by the controller 56 as appropriate to cause the controlleddevice 64 and/or 66 to undertake the action represented by the commandsignal. The logic then ends, to recommence at start state 100 uponcompletion of the command.

In contrast, when no preamble is detected at decision diamond 110 duringthe wake up period, the receiver 40 is deenergized and the oscillatorreturned to the intermediate frequency at block 114 for a short “nap”period of, e.g., two and a half milliseconds. After its nap the receiver40 is again energized for a short wake up period at block 116, with theclock speed being increased to the high frequency.

When the receiver 40 is energized at block 116, the logic moves todecision diamond 118 to determine whether a preamble has been detectedduring the wake-up time. If so, the receiver remains energized at block112, and the command signal from the remote control device 28 isprocessed by the controller 56. The logic then ends, to recommence atstart state 100 upon completion of the command.

In contrast, when no preamble is detected at decision diamond 118 duringthe wake up period, the receiver 40 is deenergized at block 120 for along sleep, e.g., fifty four milliseconds. At this point, the clockfrequency of the controller 56 is reduced to the low (e.g., 30 KHz)speed at block 122, and the logic loops back to decision diamond 102 toreturn a positive test result at the end of the long sleep period.

In this way, the system 10 waits as long a time as possible betweenwake-up cycles of the receiver 40 to reduce power consumption, and yetis assured of detecting the first transmission that occurs.

The present invention also contemplates further logic in the controller56 for adaptively establishing a noise threshold to account for changinglevels of ambient rf noise. Generally, the comparator circuit andcontroller 56 shown in FIG. 2 ignore signals that have signal strengthsbelow a nominal noise threshold. However, the noise threshold (abovewhich a carrier must be detected to begin the above logic) can beadjusted as follows to account for changing ambient rf noise levels.Initially, when no control signals have been detected, the noisethreshold for both filters 54, 60 is set relatively low. When thecontroller 56 determines that a false carrier has been detected, however(as might be indicated by attempting to process a signal withoutsuccessfully decoding the signal), the controller 56 raises the noisethreshold above which a carrier must be detected to activate the logicabove.

While the particular LOW POWER RF CONTROL SYSTEM as herein shown anddescribed in detail is fully capable of attaining the above-describedobjects of the invention, it is to be understood that it is thepresently preferred embodiment of the present invention and is thusrepresentative of the subject matter which is broadly contemplated bythe present invention, that the scope of the present invention fullyencompasses other embodiments which may become obvious to those skilledin the art, and that the scope of the present invention is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more”. It isnot necessary for a device or method to address each and every problemsought to be solved by the present invention, for it to be encompassedby the present claims. Furthermore, no element, component, or methodstep in the present disclosure is intended to be dedicated to the publicregardless of whether the element, component, or method step isexplicitly recited in the claims. Absent express definitions herein,claim terms are to be given all ordinary and accustomed meanings thatare not irreconcilable with the present specification and file history.

1. A control system for operating a component at least in part inresponse to a signal from a remote control device manipulable by a user,the system comprising: at least one receiver configured for processing asignal when being activated; at least one controller causing thereceiver to be activated periodically during a wake-up event comprisingat least an activation period (B, B′, B″) and deactivated if no signalis detected during the wake-up event; wherein the signal includes atleast one preamble pulse (P) during a pre-synchronization cycle followedby at least a data command signal, and wherein the receiver is activatedaccording to a series of wake-up events in such a way that, during thewhole duration of a pre-synchronization cycle, the receiver is at leastactivated during two activation periods and at most two activationperiods occur during one and a same preamble pulse.
 2. The controlsystem of claim 1 wherein: the at least one receiver is associated withthe component and configured for processing the signal; and the at leastone controller is associated with the component and controlling thereceiver, the controller causing the receiver to be energized accordingto an energization paradigm selected from the group consisting of:energizing for a first energized period, then deenergizing for a shortperiod if no preamble pulse is detected, then energizing for a secondenergized period, and then deenergizing, at least if no preamble pulseis detected, for period longer than the short period, prior toreenergizing the receiver; and energizing for a first time period andthen energizing for a second time period after a rest period the lengthof which ensures detection, in at least one of the time periods, of apreamble pulse if a preamble has been generated; wherein when thereceiver is energized during an off period of an existing preamble, thereceiver can be energized a second time after a rest period, the lengthof which ensures detection in at least one of the time periods of apreamble pulse, wherein when the controller causes the receiver to beenergized, an activation duration of the receiver is substantiallyshorter than the period of a preamble pulse.
 3. The system of claim 2,wherein each preamble pulse has a duty cycle in excess of fifty percent(50%).
 4. The system of claim 3, wherein the signal includes at leastsix preamble pulses.
 5. The system of claim 2, comprising a fast filterand a slow filter each electrically interposed between the receiver andcontroller.
 6. The system of claim 2, wherein the controller operates ata low clock frequency during at least most of the long period and at ahigh clock frequency at least when the receiver is energized.
 7. Thesystem of claim 6, wherein the controller operates at an intermediatefrequency between the low and high frequencies just prior to energizingthe receiver after the long period.
 8. The system of claim 2, comprisingat least one bypass capacitor electrically connected to the receiver andto ground, the bypass capacitor having a capacitance of below fivehundred picoFarads (500 pF).
 9. The system of claim 8, comprising pluralbypass capacitors, at least one having a capacitance not substantiallymore than one hundred picoFarads (100 pF).
 10. The system of claim 2,comprising at least one surface acoustic wave (SAW) resonator circuitestablishing an intermediate frequency (IF) oscillator for the receiver.11. The system of claim 10, comprising an LC filter associated with thereceiver for filtering an IF signal.
 12. The system of claim 2, whereinthe component is powered by at least one battery, and the system furthercomprises a DC-DC down converter electrically interposed between thebattery and receiver to provide a voltage to the receiver.
 13. Thesystem of claim 2; comprising the component and a motor coupled to anoperator of a component and controlled by the controller, the componentbeing selected from the group of components consisting of windowcoverings, awnings, skylight covers, and screens.
 14. The system ofclaim 2, wherein the controller adaptively adjusts a noise thresholdabove which a carrier must be detected to indicate the presence of acontrol signal.
 15. The system of claim 2, wherein the controller causesthe receiver to be energized according to the following paradigm:energizing for a first energized period, then deenergizing for a shortperiod if no preamble signal is detected, then energizing for a secondenergized period, and then deenergizing, at least if no preamble signalis detected, for period longer than the short period, prior toreenergizing the receiver.
 16. The system of claim 2, wherein thecontroller causes the receiver to be energized according to thefollowing paradigm: energizing for a first time period and thenenergizing for a second time period after a staggered rest period thelength of which equals an integer multiple of one-half of a pulse periodplus or minus a time delta, the time delta being less than one-half thepulse period.
 17. The system of claim 2, wherein the controller causesthe receiver to be energized according to the following paradigm:energizing the receiver once sometime within a period of a relativelylong preamble pulse.
 18. The system of claim 2, wherein the activationduration is approximately 80 microseconds when the period of thepreamble pulse is approximately 5000 microseconds.
 19. The controlsystem of claim 1 wherein: the at least one receiver is associated withthe component and configured for processing the signal; and the at leastone controller is associated with the component and controlling thereceiver, wherein the controller operates at a low clock frequencyduring at least most of a receiver sleep period and at a high clockfrequency at least when the receiver is energized.
 20. The system ofclaim 19, wherein the controller operates at an intermediate frequencybetween the low and high frequencies just prior to energizing thereceiver after the receiver sleep period.
 21. The system of claim 19,wherein the signal includes a preamble including plural pulses, eachhaving a duty cycle in excess of fifty percent (50%).
 22. The system ofclaim 21, wherein the preamble includes at least six pulses.
 23. Thesystem of claim 19, comprising a fast filter and a slow filter eachelectrically interposed between the receiver and controller.
 24. Thesystem of claim 19, comprising at least one bypass capacitorelectrically connected to the receiver and to ground, the bypasscapacitor having a capacitance of below five hundred picoFarads (500pF).
 25. The system of claim 24, comprising plural bypass capacitors, atleast one having a capacitance not substantially more than one hundredpicoFarads (100 pF).
 26. The system of claim 19, comprising at least onesurface acoustic wave (SAW) resonator circuit establishing anintermediate frequency (IF) oscillator for the receiver.
 27. The systemof claim 26, comprising an LC filter associated with the receiver forfiltering an IF signal.
 28. The system of claim 19, wherein thecomponent is powered by at least one battery, and the system furthercomprises a DC-DC down converter electrically interposed between thebattery and receiver to provide a voltage to the receiver.
 29. Thesystem of claim 19, comprising the component and a motor coupled to anoperator of a component and controlled by the controller, the componentbeing selected from the group of components consisting of windowcoverings, awnings, skylight covers, and screens.
 30. The system ofclaim 19, wherein the controller adaptively adjusts a noise thresholdabove which a carrier must be detected to indicate the presence of acontrol signal.
 31. The control system of claim 1 wherein: the at leastone receiver is associated with the component and configured forprocessing the signal; the at least one controller is associated withthe component and controlling the receiver; and the system furthercomprises at least one bypass capacitor electrically connected to thereceiver and to ground, the bypass capacitor having a capacitance ofbelow five hundred picoFarads (500 pF), wherein when the controllercauses the receiver to be energized, wherein when the receiver isenergized during an off period of an existing preamble, the receiver canbe energized a second time after a rest period, the length of whichensures detection in at least one of the time periods of a preamblepulse, and an activation duration of the receiver is substantiallyshorter than the period of a preamble pulse.
 32. The system of claim 31,comprising plural bypass capacitors, at least one having a capacitancenot substantially more than one hundred picoFarads (100 pF).
 33. Thesystem of claim 31, wherein the signal includes a preamble includingplural pulses, each having a duty cycle in excess of fifty percent(50%).
 34. The system of claim 33, wherein the preamble includes atleast six pulses.
 35. The system of claim 31, comprising a fast filterand a slow filter each electrically interposed between the receiver andcontroller.
 36. The system of claim 31, wherein the controller operatesat a low clock frequency during at least most of a long receiver sleepperiod and at a high clock frequency at least when the receiver isenergized.
 37. The system of claim 36, wherein the controller operatesat an intermediate frequency between the low and high frequencies justprior to energizing the receiver after the long receiver sleep period.38. The system of claim 31, comprising at least one surface acousticwave (SAW) resonator circuit establishing an intermediate frequency (IF)oscillator for the receiver.
 39. The system of claim 38, comprising anLC filter associated with the receiver for filtering an IF signal. 40.The system of claim 31, wherein the component is powered by at least onebattery, and the system further comprises a DC-DC down converterelectrically interposed between the battery and receiver to provide avoltage to the receiver.
 41. The system of claim 31, comprising thecomponent and a motor coupled to an operator of a component andcontrolled by the controller, the component being selected from thegroup of components consisting of window coverings, awnings, skylightcovers, and screens.
 42. The system of claim 31, wherein the controlleradaptively adjusts a noise threshold above which a carrier must bedetected to indicate the presence of a control signal.
 43. The controlsystem of claim 1 wherein: the at least one receiver is associated withthe component and configured for processing the signal; the at least onecontroller is associated with the component and controlling thereceiver; and the system further comprises at least one surface acousticwave (SAW) resonator circuit establishing an intermediate frequency (IF)oscillator for the receiver, wherein the preamble pulse is not a datacommand signal, wherein when the controller causes the receiver to beenergized, wherein when the receiver is energized during an off periodof an existing preamble, the receiver can be energized a second timeafter a rest period, the length of which ensures detection in at leastone of the time periods of a preamble pulse, and an activation durationof the receiver is substantially shorter than the period of a preamblepulse.
 44. The system of claim 43, comprising an LC filter associatedwith the receiver for filtering an IF signal.
 45. The system of claim43, wherein the signal includes a preamble including plural pulses, eachhaving a duty cycle in excess of fifty percent (50%).
 46. The system ofclaim 45, wherein the preamble includes at least six pulses.
 47. Thesystem of claim 43, comprising a fast filter and a slow filter eachelectrically interposed between the receiver and the controller.
 48. Thesystem of claim 43, wherein the controller operates at a low clockfrequency during at least most of a long sleep period and at a highclock frequency at least when the receiver is energized.
 49. The systemof claim 48, wherein the controller operates at an intermediatefrequency between the low and high frequencies just prior to energizingthe receiver after the long period.
 50. The system of claim 43,comprising at least one bypass capacitor electrically connected to thereceiver and to ground, the bypass capacitor having a capacitance ofbelow five hundred picoFarads (500 pF).
 51. The system of claim 50,comprising plural bypass capacitors, at least one having a capacitancenot substantially more than one hundred picoFarads (100 pF).
 52. Thesystem of claim 43, wherein the component is powered by at least onebattery, and the system further comprises a DC-DC down converterelectrically interposed between the battery and receiver to provide avoltage to the receiver.
 53. The system of claim 43, comprising thecomponent and a motor coupled to an operator of a component andcontrolled by the controller, the component being selected from thegroup of components consisting of window coverings, awnings, skylightcovers, and screens.
 54. The system of claim 43, wherein the controlleradaptively adjusts a noise threshold above which a carrier must bedetected to indicate the presence of a control signal.
 55. The controlsystem of claim 1 wherein: the at least one receiver is associated withthe component and configured for processing the signal; the at least onecontroller is associated with the component and controlling thereceiver; and the system further comprises a DC-DC down converterelectrically interposed between a battery and receiver to provide avoltage to the receiver, wherein when the controller causes the receiverto be energized, wherein when the receiver is energized during an offperiod of an existing preamble, the receiver can be energized a secondtime after a rest period, the length of which ensures detection in atleast one of the time periods of a preamble pulse, and an activationduration of the receiver is substantially shorter than the period of apreamble pulse.
 56. The system of claim 55, wherein the signal includesa preamble including plural pulses, each having a duty cycle in excessof fifty percent (50%).
 57. The system of claim 56, wherein the preambleincludes at least six pulses.
 58. The system of claim 57, comprising afast filter and a slow filter each electrically interposed between thereceiver and the controller.
 59. The system of claim 55, wherein thecontroller operates at a low clock frequency during at least most of along period and at a high clock frequency at least when the receiver isenergized.
 60. The system of claim 59, wherein the controller operatesat an intermediate frequency between the low and high frequencies justprior to energizing the receiver after the long period.
 61. The systemof claim 55, comprising at least one bypass capacitor electricallyconnected to the receiver and to ground, the bypass capacitor having acapacitance of below five hundred picoFarads (500 pF).
 62. The system ofclaim 61, comprising plural bypass capacitors, at least one having acapacitance not substantially more than one hundred picoFarads (100 pF).63. The system of claim 55, comprising at least one surface acousticwave (SAW) resonator circuit establishing an intermediate frequency (IF)oscillator for the receiver.
 64. The system of claim 63, comprising anLC filter associated with the receiver for filtering an IF signal. 65.The system of claim 55, wherein the component is powered by at least onebattery, and the system further comprises a DC-DC down converterelectrically interposed between the battery and receiver to provide avoltage to the receiver.
 66. The system of claim 55, comprising thecomponent and a motor coupled to an operator of a component andcontrolled by the controller, the component being selected from thegroup of components consisting of window coverings, awnings, skylightcovers, and screens.
 67. The system of claim 55, wherein the controlleradaptively adjusts a noise threshold above which a carrier must bedetected to indicate the presence of a control signal.
 68. The controlsystem of claim 1 wherein: the at least one receiver is associated withthe component and configured for processing the signal; and the at leastone controller is associated with the component and controlling thereceiver, wherein the controller adaptively adjusts a noise thresholdabove which a carrier must be detected to indicate the presence of acontrol signal.
 69. The system of claim 68, wherein the controlleroperates at an intermediate frequency between low and high frequenciesjust prior to energizing the receiver after a receiver sleep period. 70.The system of claim 68, wherein the signal includes a preamble includingplural pulses, each having a duty cycle in excess of fifty percent(50%).
 71. The system of claim 70, wherein the preamble includes atleast six pulses.
 72. The system of claim 68, comprising a fast filterand a slow filter each electrically interposed between the receiver andcontroller.
 73. The system of claim 68, comprising at least one bypasscapacitor electrically connected to the receiver and to ground, thebypass capacitor having a capacitance of below five hundred picoFarads(500 pF).
 74. The system of claim 73, comprising plural bypasscapacitors, at least one having a capacitance not substantially morethan one hundred picoFarads (100 pF).
 75. The system of claim 68,comprising at least one surface acoustic wave (SAW) resonator circuitestablishing an intermediate frequency (IF) oscillator for the receiver.76. The system of claim 75, comprising an LC filter associated with thereceiver for filtering an IF signal.
 77. The system of claim 68, whereinthe component is powered by at least one battery, and the system furthercomprises a DC-DC down converter electrically interposed between thebattery and receiver to provide a voltage to the receiver.
 78. Thesystem of claim 68, comprising the component and a motor coupled to anoperator of a component and controlled by the controller, the componentbeing selected from the group of components consisting of windowcoverings, awnings, skylight covers, and screens.
 79. The control systemof claim 1, wherein the time period between the end of a first wake-upevent and the beginning of a subsequent wake-up event is superior to 70%of the whole duration of the pre-synchronization cycle.